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Swanepoel CM, Mueller JL. Out with the old, in with the new: Meiotic driving of sex chromosome evolution. Semin Cell Dev Biol 2024; 163:14-21. [PMID: 38664120 DOI: 10.1016/j.semcdb.2024.04.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2023] [Revised: 04/19/2024] [Accepted: 04/20/2024] [Indexed: 05/26/2024]
Abstract
Chromosomal regions with meiotic drivers exhibit biased transmission (> 50 %) over their competing homologous chromosomal region. These regions often have two prominent genetic features: suppressed meiotic crossing over and rapidly evolving multicopy gene families. Heteromorphic sex chromosomes (e.g., XY) often share these two genetic features with chromosomal regions exhibiting meiotic drive. Here, we discuss parallels between meiotic drive and sex chromosome evolution, how the divergence of heteromorphic sex chromosomes can be influenced by meiotic drive, experimental approaches to study meiotic drive on sex chromosomes, and meiotic drive in traditional and non-traditional model organisms with high-quality genome assemblies. The newly available diversity of high-quality sex chromosome sequences allows us to revisit conventional models of sex chromosome evolution through the lens of meiotic drive.
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Affiliation(s)
- Callie M Swanepoel
- Department of Human Genetics, University of Michigan Medical School, 1241 E. Catherine St, Ann Arbor, MI, USA
| | - Jacob L Mueller
- Department of Human Genetics, University of Michigan Medical School, 1241 E. Catherine St, Ann Arbor, MI, USA.
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2
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Li J, Song S, Zhang J. Where Are the Formerly Y-linked Genes in the Ryukyu Spiny Rat that has Lost its Y Chromosome? Genome Biol Evol 2024; 16:evae046. [PMID: 38478711 PMCID: PMC10959550 DOI: 10.1093/gbe/evae046] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/07/2024] [Indexed: 03/23/2024] Open
Abstract
It has been predicted that the highly degenerate mammalian Y chromosome will be lost eventually. Indeed, Y was lost in the Ryukyu spiny rat Tokudaia osimensis, but the fate of the formerly Y-linked genes is not completely known. We looked for all 12 ancestrally Y-linked genes in a draft T. osimensis genome sequence. Zfy1, Zfy2, Kdm5d, Eif2s3y, Usp9y, Uty, and Ddx3y are putatively functional and are now located on the X chromosome, whereas Rbmy, Uba1y, Ssty1, Ssty2, and Sry are missing or pseudogenized. Tissue expressions of the mouse orthologs of the retained genes are significantly broader/higher than those of the lost genes, suggesting that the destinies of the formerly Y-linked genes are related to their original expressions. Interestingly, patterns of gene retention/loss are significantly more similar than by chance across four rodent lineages where Y has been independently lost, indicating a level of certainty in the fate of Y-linked genes even when the chromosome is gone.
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Affiliation(s)
- Jiachen Li
- Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Siliang Song
- Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Jianzhi Zhang
- Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, MI 48109, USA
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3
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Luchsinger-Morcelle SJ, Gribnau J, Mira-Bontenbal H. Orchestrating Asymmetric Expression: Mechanisms behind Xist Regulation. EPIGENOMES 2024; 8:6. [PMID: 38390897 PMCID: PMC10885031 DOI: 10.3390/epigenomes8010006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2023] [Revised: 01/19/2024] [Accepted: 01/22/2024] [Indexed: 02/24/2024] Open
Abstract
Compensation for the gene dosage disequilibrium between sex chromosomes in mammals is achieved in female cells by repressing one of its X chromosomes through a process called X chromosome inactivation (XCI), exemplifying the control of gene expression by epigenetic mechanisms. A critical player in this mechanism is Xist, a long, non-coding RNA upregulated from a single X chromosome during early embryonic development in female cells. Over the past few decades, many factors involved at different levels in the regulation of Xist have been discovered. In this review, we hierarchically describe and analyze the different layers of Xist regulation operating concurrently and intricately interacting with each other to achieve asymmetric and monoallelic upregulation of Xist in murine female cells. We categorize these into five different classes: DNA elements, transcription factors, other regulatory proteins, long non-coding RNAs, and the chromatin and topological landscape surrounding Xist.
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Affiliation(s)
| | - Joost Gribnau
- Department of Developmental Biology, Erasmus MC, University Medical Center, 3015 GD Rotterdam, The Netherlands
| | - Hegias Mira-Bontenbal
- Department of Developmental Biology, Erasmus MC, University Medical Center, 3015 GD Rotterdam, The Netherlands
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4
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Roy SW. Did the creeping vole sex chromosomes evolve through a cascade of adaptive responses to a selfish x chromosome? Bioessays 2023; 45:e2100164. [PMID: 37941456 DOI: 10.1002/bies.202100164] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2021] [Revised: 10/07/2023] [Accepted: 10/10/2023] [Indexed: 11/10/2023]
Abstract
The creeping vole Microtus oregoni exhibits remarkably transformed sex chromosome biology, with complete chromosome drive/drag, X-Y fusions, sex reversed X complements, biased X inactivation, and X chromosome degradation. Beginning with a selfish X chromosome, I propose a series of adaptations leading to this system, each compensating for deleterious consequences of the preceding adaptation: (1) YY embryonic inviability favored evolution of a selfish feminizing X chromosome; (2) the consequent Y chromosome transmission disadvantage favored X-Y fusion ("XP "); (3) Xist-based silencing of Y-derived XP genes favored a second X-Y fusion ("XM "); (4) X chromosome dosage-related costs in XP XM males favored the evolution of XM loss during spermatogenesis; (5) X chromosomal dosage-related costs in XM 0 females favored the evolution of XM drive during oogenesis; and (6) degradation of the non-recombining XP favored the evolution of biased X chromosome inactivation. I discuss recurrent rodent sex chromosome transformation, and selfish genes as a constructive force in evolution.
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5
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Sykes NTB, Kolora SRR, Sudmant PH, Owens GL. Rapid turnover and evolution of sex-determining regions in Sebastes rockfishes. Mol Ecol 2023; 32:5013-5027. [PMID: 37548650 DOI: 10.1111/mec.17090] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2023] [Revised: 07/21/2023] [Accepted: 07/25/2023] [Indexed: 08/08/2023]
Abstract
Nature has evolved a wealth of sex determination (SD) mechanisms, driven by both genetic and environmental factors. Recent studies of SD in fishes have shown that not all taxa fit the classic paradigm of sex chromosome evolution and diverse SD methods can be found even among closely related species. Here, we apply a suite of genomic approaches to investigate sex-biased genomic variation in eight species of Sebastes rockfish found in the northeast Pacific Ocean. Using recently assembled chromosome-level rockfish genomes, we leverage published sequence data to identify disparate sex chromosomes and sex-biased loci in five species. We identify two putative male sex chromosomes in S. diaconus, a single putative sex chromosome in the sibling species S. carnatus and S. chrysomelas, and an unplaced sex determining contig in the sibling species S. miniatus and S. crocotulus. Our study provides evidence for disparate means of sex determination within a recently diverged set of species and sheds light on the diverse origins of sex determination mechanisms present in the animal kingdom.
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Affiliation(s)
- Nathan T B Sykes
- Department of Biology, University of Victoria, Victoria, British Columbia, Canada
| | - Sree Rohit Raj Kolora
- Department of Integrative Biology, University of California, Berkeley, California, USA
| | - Peter H Sudmant
- Department of Integrative Biology, University of California, Berkeley, California, USA
- Center for Computational Biology, University of California, Berkeley, California, USA
| | - Gregory L Owens
- Department of Biology, University of Victoria, Victoria, British Columbia, Canada
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6
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Barutc AR, Frit AJ, McCor RP, Nick JA, Asla M. Heat shock factor 5 establishes the male germ-line meiotic sex chromosome inactivation through regulation of Smarca4. Heliyon 2023; 9:e15194. [PMID: 37206036 PMCID: PMC10189179 DOI: 10.1016/j.heliyon.2023.e15194] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2022] [Revised: 03/28/2023] [Accepted: 03/29/2023] [Indexed: 05/21/2023] Open
Abstract
Meiotic sex chromosome inactivation is an essential event in male germ cell development, which is directed by DNA damage response signaling independent of Xist RNA to silence the transcription activity of the sex chromosomes. However, the specific mechanism of establishment and maintenance of meiotic chromosome silencing is still unclear. Here we identify the HSF5 as a testicular specific protein and the expression of which was at the onset of meiosis pachytene stage to round sperm. When the function of the HSF5 was lost, meiosis sex chromosome remodeling and silencing fail, followed by activation of CHK2 checkpoint leads to germ cell apoptosis. Furthermore, we found that SMARCA4 in the linking the HSF5 to MSCI and uncover additional factors with meiotic sex chromosome remodeling. Together, our results demonstrate a requirement for HSF5 activity in spermatogenesis and suggest a role for the mammalian HSF5-SMARCA4 in programmed meiotic sex chromosome remodeling and silencing events that take place during meiosis.
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Affiliation(s)
- A Rasim Barutc
- Department of Statistics, Faculty of Science, King Abdulaziz University, Jeddah, 21551, Saudi Arabia
- Program in Systems Biology, University of Massachusetts Medical School, Worcester, MA 01605, USA
| | - Andrew J. Frit
- Department of Biochemistry, University of Vermont College of Medicine, Burlington, VT 05405, USA
| | - Rachel P. McCor
- Department of Statistics, Faculty of Science, King Abdulaziz University, Jeddah, 21551, Saudi Arabia
| | - Jeffrey A. Nick
- Department of Statistics, Faculty of Science, King Abdulaziz University, Jeddah, 21551, Saudi Arabia
| | - Muhammad Asla
- Department of Statistics, Faculty of Science, King Abdulaziz University, Jeddah, 21551, Saudi Arabia
- Department of Biochemistry, University of Vermont College of Medicine, Burlington, VT 05405, USA
- Corresponding author. Department of Statistics, Faculty of Science, King Abdulaziz University, Jeddah, 21551, Saudi Arabia.
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7
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Chen W, Zhou W, Li Q, Mao X. Sex differences in gene expression and alternative splicing in the Chinese horseshoe bat. PeerJ 2023; 11:e15231. [PMID: 37123006 PMCID: PMC10135408 DOI: 10.7717/peerj.15231] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2022] [Accepted: 03/24/2023] [Indexed: 05/02/2023] Open
Abstract
Sexually dimorphic traits are common in sexually reproducing organisms and can be encoded by differential gene regulation between males and females. Although alternative splicing is common mechanism in generating transcriptional diversity, its role in generating sex differences relative to differential gene expression is less clear. Here, we investigate the relative roles of differential gene expression and alternative splicing between male and female the horseshoe bat species, Rhinolophus sinicus. Horseshoe bats are an excellent model to study acoustic differences between sexes. Using RNA-seq analyses of two somatic tissues (brain and liver) from males and females of the same population, we identified 3,471 and 2,208 differentially expressed genes between the sexes (DEGs) in the brain and liver, respectively. DEGs were enriched with functional categories associated with physiological difference of the sexes (e.g.,gamete generation and energy production for reproduction in females). In addition, we also detected many differentially spliced genes between the sexes (DSGs, 2,231 and 1,027 in the brain and liver, respectively) which were mainly involved in regulation of RNA splicing and mRNA metabolic process. Interestingly, we found a significant enrichment of DEGs on the X chromosome, but not for DSGs. As for the extent of overlap between the two sets of genes, more than expected overlap of DEGs and DSGs was observed in the brain but not in the liver. This suggests that more complex tissues, such as the brain, may require the intricate and simultaneous interplay of both differential gene expression and splicing of genes to govern sex-specific functions. Overall, our results support that variation in gene expression and alternative splicing are important and complementary mechanisms governing sex differences.
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Affiliation(s)
- Wenli Chen
- School of Ecological and Environmental Sciences, East China Normal University, Shanghai, China
| | - Weiwei Zhou
- School of Ecological and Environmental Sciences, East China Normal University, Shanghai, China
| | - Qianqian Li
- School of Ecological and Environmental Sciences, East China Normal University, Shanghai, China
| | - Xiuguang Mao
- School of Ecological and Environmental Sciences, East China Normal University, Shanghai, China
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8
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Chang CH, Mejia Natividad I, Malik HS. Expansion and loss of sperm nuclear basic protein genes in Drosophila correspond with genetic conflicts between sex chromosomes. eLife 2023; 12:85249. [PMID: 36763410 PMCID: PMC9917458 DOI: 10.7554/elife.85249] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2022] [Accepted: 01/04/2023] [Indexed: 02/11/2023] Open
Abstract
Many animal species employ sperm nuclear basic proteins (SNBPs) or protamines to package sperm genomes tightly. SNBPs vary across animal lineages and evolve rapidly in mammals. We used a phylogenomic approach to investigate SNBP diversification in Drosophila species. We found that most SNBP genes in Drosophila melanogaster evolve under positive selection except for genes essential for male fertility. Unexpectedly, evolutionarily young SNBP genes are more likely to be critical for fertility than ancient, conserved SNBP genes. For example, CG30056 is dispensable for male fertility despite being one of three SNBP genes universally retained in Drosophila species. We found 19 independent SNBP gene amplification events that occurred preferentially on sex chromosomes. Conversely, the montium group of Drosophila species lost otherwise-conserved SNBP genes, coincident with an X-Y chromosomal fusion. Furthermore, SNBP genes that became linked to sex chromosomes via chromosomal fusions were more likely to degenerate or relocate back to autosomes. We hypothesize that autosomal SNBP genes suppress meiotic drive, whereas sex-chromosomal SNBP expansions lead to meiotic drive. X-Y fusions in the montium group render autosomal SNBPs dispensable by making X-versus-Y meiotic drive obsolete or costly. Thus, genetic conflicts between sex chromosomes may drive SNBP rapid evolution during spermatogenesis in Drosophila species.
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Affiliation(s)
- Ching-Ho Chang
- Division of Basic Sciences, Fred Hutchinson Cancer Center, Seattle, United States
| | - Isabel Mejia Natividad
- Division of Basic Sciences, Fred Hutchinson Cancer Center, Seattle, United States.,Howard Hughes Medical Institute, Fred Hutchinson Cancer Center, Seattle, United States
| | - Harmit S Malik
- Division of Basic Sciences, Fred Hutchinson Cancer Center, Seattle, United States.,Howard Hughes Medical Institute, Fred Hutchinson Cancer Center, Seattle, United States
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9
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Somatic XIST activation and features of X chromosome inactivation in male human cancers. Cell Syst 2022; 13:932-944.e5. [PMID: 36356577 DOI: 10.1016/j.cels.2022.10.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2021] [Revised: 05/09/2022] [Accepted: 10/04/2022] [Indexed: 11/11/2022]
Abstract
Expression of the non-coding RNA XIST is essential for initiating X chromosome inactivation (XCI) during early development in female mammals. As the main function of XCI is to enable dosage compensation of chromosome X genes between the sexes, XCI and XIST expression are generally absent in male normal tissues, except in germ cells and in individuals with supernumerary X chromosomes. Via a systematic analysis of public sequencing data of both cancerous and normal tissues, we report that XIST is somatically activated in a subset of male human cancers across diverse lineages. Some of these cancers display hallmarks of XCI, including silencing of gene expression, reduced chromatin accessibility, and increased DNA methylation across chromosome X, suggesting that the developmentally restricted, female-specific program of XCI can be somatically accessed in male cancers.
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10
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Zhang S, Wu Z, Ma D, Zhai J, Han X, Jiang Z, Liu S, Xu J, Jiao P, Li Z. Chromosome-scale assemblies of the male and female Populus euphratica genomes reveal the molecular basis of sex determination and sexual dimorphism. Commun Biol 2022; 5:1186. [PMCID: PMC9636151 DOI: 10.1038/s42003-022-04145-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2022] [Accepted: 10/20/2022] [Indexed: 11/06/2022] Open
Abstract
Reference-quality genomes of both sexes are essential for studying sex determination and sex-chromosome evolution, as their gene contents and expression profiles differ. Here, we present independent chromosome-level genome assemblies for the female (XX) and male (XY) genomes of desert poplar (Populus euphratica), resolving a 22.7-Mb X and 24.8-Mb Y chromosome. We also identified a relatively complete 761-kb sex-linked region (SLR) in the peritelomeric region on chromosome 14 (Y). Within the SLR, recombination around the partial repeats for the feminizing factor ARR17 (ARABIDOPSIS RESPONSE REGULATOR 17) was potentially suppressed by flanking palindromic arms and the dense accumulation of retrotransposons. The inverted small segments S1 and S2 of ARR17 exhibited relaxed selective pressure and triggered sex determination by generating 24-nt small interfering RNAs that induce male-specific hyper-methylation at the promoter of the autosomal targeted ARR17. We also detected two male-specific fusion genes encoding proteins with NB-ARC domains at the breakpoint region of an inversion in the SLR that may be responsible for the observed sexual dimorphism in immune responses. Our results show that the SLR appears to follow proposed evolutionary dynamics for sex chromosomes and advance our understanding of sex determination and the evolution of sex chromosomes in Populus. Reference-quality genomes of both sexes of the dioecious tree species, Populus euphratica, provide further insight into the evolution of Populus sex chromosomes and highlight male-specific fusion genes that may contribute to sexual dimorphism.
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Affiliation(s)
- Shanhe Zhang
- grid.443240.50000 0004 1760 4679College of Life Sciences and Technology, Tarim University/Key Laboratory of Protection and Utilization of Biological Resources in Tarim Basin, Xinjiang Production & Construction Corps/Research Center of Populus Euphratica, Aral, 843300 China
| | - Zhihua Wu
- grid.453534.00000 0001 2219 2654College of Chemistry and Life Sciences, Zhejiang Normal University, Jinhua, 321004 China
| | - De Ma
- grid.410753.4Novogene Bioinformatics Institute, Beijing, 100083 China
| | - Juntuan Zhai
- grid.443240.50000 0004 1760 4679College of Life Sciences and Technology, Tarim University/Key Laboratory of Protection and Utilization of Biological Resources in Tarim Basin, Xinjiang Production & Construction Corps/Research Center of Populus Euphratica, Aral, 843300 China
| | - Xiaoli Han
- grid.443240.50000 0004 1760 4679College of Life Sciences and Technology, Tarim University/Key Laboratory of Protection and Utilization of Biological Resources in Tarim Basin, Xinjiang Production & Construction Corps/Research Center of Populus Euphratica, Aral, 843300 China
| | - Zhenbo Jiang
- grid.443240.50000 0004 1760 4679College of Life Sciences and Technology, Tarim University/Key Laboratory of Protection and Utilization of Biological Resources in Tarim Basin, Xinjiang Production & Construction Corps/Research Center of Populus Euphratica, Aral, 843300 China
| | - Shuo Liu
- Hubei Provincial Key Laboratory for Protection and Application of Special Plant Germplasm in Wuling Area of China, College of Life Sciences, South-Central Minzu University, Wuhan, 430074 China
| | - Jingdong Xu
- Hubei Provincial Key Laboratory for Protection and Application of Special Plant Germplasm in Wuling Area of China, College of Life Sciences, South-Central Minzu University, Wuhan, 430074 China
| | - Peipei Jiao
- grid.443240.50000 0004 1760 4679College of Life Sciences and Technology, Tarim University/Key Laboratory of Protection and Utilization of Biological Resources in Tarim Basin, Xinjiang Production & Construction Corps/Research Center of Populus Euphratica, Aral, 843300 China
| | - Zhijun Li
- grid.443240.50000 0004 1760 4679College of Life Sciences and Technology, Tarim University/Key Laboratory of Protection and Utilization of Biological Resources in Tarim Basin, Xinjiang Production & Construction Corps/Research Center of Populus Euphratica, Aral, 843300 China
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11
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Bentz EJ, Ophir AG. Chromosome-scale genome assembly of the African giant pouched rat (Cricetomys ansorgei) and evolutionary analysis reveals evidence of olfactory specialization. Genomics 2022; 114:110521. [PMID: 36351561 DOI: 10.1016/j.ygeno.2022.110521] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2022] [Revised: 10/28/2022] [Accepted: 11/04/2022] [Indexed: 11/07/2022]
Abstract
The Southern giant pouched rat, Cricetomys ansorgei, is a large rodent best known for its ability to detect landmines using its impressive sense of smell. Their powerful chemosensory abilities enable subtle discrimination of chemical social signals, and female pouched rats demonstrate a unique reproductive physiology hypothesized to be mediated by pheromonal mechanisms. Thus, C. ansorgei represents a novel mammalian model for chemosensory physiology, social behavior, and pheromonal control of reproductive physiology. We present the first chromosome-scale genomic sequence of the pouched rat encoding 22,671 protein coding genes, including 1571 olfactory receptors, and provide a glance into the evolutionary history of this species. Functional enrichment analysis reveals genetic expansions specific to the pouched rat are enriched for functions related to olfactory specialization. Overall, this assembly is of reference-quality, and will serve as a useful and informative genomic sequence on which we can confidently base future molecular research involving the pouched rat.
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Affiliation(s)
- Ehren J Bentz
- Department of Psychology, Cornell University, Ithaca, NY, USA.
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12
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Moore EC, Thomas GWC, Mortimer S, Kopania EEK, Hunnicutt KE, Clare-Salzler ZJ, Larson EL, Good JM. The evolution of widespread recombination suppression on the dwarf hamster (Phodopus) X chromosome. Genome Biol Evol 2022; 14:6596369. [PMID: 35642315 PMCID: PMC9185382 DOI: 10.1093/gbe/evac080] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/25/2022] [Indexed: 11/24/2022] Open
Abstract
The X chromosome of therian mammals shows strong conservation among distantly related species, limiting insights into the distinct selective processes that have shaped sex chromosome evolution. We constructed a chromosome-scale de novo genome assembly for the Siberian dwarf hamster (Phodopus sungorus), a species reported to show extensive recombination suppression across an entire arm of the X chromosome. Combining a physical genome assembly based on shotgun and long-range proximity ligation sequencing with a dense genetic map, we detected widespread suppression of female recombination across ∼65% of the Phodopus X chromosome. This region of suppressed recombination likely corresponds to the Xp arm, which has previously been shown to be highly heterochromatic. Using additional sequencing data from two closely related species (P. campbelli and P. roborovskii), we show that recombination suppression on Xp appears to be independent of major structural rearrangements. The suppressed Xp arm was enriched for several transposable element families and de-enriched for genes primarily expressed in placenta, but otherwise showed similar gene densities, expression patterns, and rates of molecular evolution when compared to the recombinant Xq arm. Phodopus Xp gene content and order was also broadly conserved relative to the more distantly related rat X chromosome. These data suggest that widespread suppression of recombination has likely evolved through the transient induction of facultative heterochromatin on the Phodopus Xp arm without major changes in chromosome structure or genetic content. Thus, substantial changes in the recombination landscape have so far had relatively subtle influences on patterns of X-linked molecular evolution in these species.
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Affiliation(s)
- Emily C Moore
- Division of Biological Sciences, The University of Montana, Missoula, Montana, 59812, USA
| | - Gregg W C Thomas
- Division of Biological Sciences, The University of Montana, Missoula, Montana, 59812, USA
| | - Sebastian Mortimer
- Division of Biological Sciences, The University of Montana, Missoula, Montana, 59812, USA
| | - Emily E K Kopania
- Division of Biological Sciences, The University of Montana, Missoula, Montana, 59812, USA
| | - Kelsie E Hunnicutt
- Department of Biological Sciences, The University of Denver, Denver, Colorado, 80208, USA
| | | | - Erica L Larson
- Department of Biological Sciences, The University of Denver, Denver, Colorado, 80208, USA
| | - Jeffrey M Good
- Division of Biological Sciences, The University of Montana, Missoula, Montana, 59812, USA
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13
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Saunders PA, Veyrunes F. Unusual Mammalian Sex Determination Systems: A Cabinet of Curiosities. Genes (Basel) 2021; 12:1770. [PMID: 34828376 PMCID: PMC8617835 DOI: 10.3390/genes12111770] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2021] [Revised: 10/29/2021] [Accepted: 11/05/2021] [Indexed: 11/21/2022] Open
Abstract
Therian mammals have among the oldest and most conserved sex-determining systems known to date. Any deviation from the standard XX/XY mammalian sex chromosome constitution usually leads to sterility or poor fertility, due to the high differentiation and specialization of the X and Y chromosomes. Nevertheless, a handful of rodents harbor so-called unusual sex-determining systems. While in some species, fertile XY females are found, some others have completely lost their Y chromosome. These atypical species have fascinated researchers for over 60 years, and constitute unique natural models for the study of fundamental processes involved in sex determination in mammals and vertebrates. In this article, we review current knowledge of these species, discuss their similarities and differences, and attempt to expose how the study of their exceptional sex-determining systems can further our understanding of general processes involved in sex chromosome and sex determination evolution.
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Affiliation(s)
- Paul A. Saunders
- Institut des Sciences de l’Evolution de Montpellier, ISEM UMR 5554 (CNRS/Université Montpellier/IRD/EPHE), 34090 Montpellier, France;
- School of Natural Sciences, University of Tasmania, Sandy Bay, TAS 7000, Australia
| | - Frédéric Veyrunes
- Institut des Sciences de l’Evolution de Montpellier, ISEM UMR 5554 (CNRS/Université Montpellier/IRD/EPHE), 34090 Montpellier, France;
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14
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Charlesworth D. Evolution: Shape-shifting vole sex determination and sex chromosomes. Curr Biol 2021; 31:R967-R969. [PMID: 34375604 DOI: 10.1016/j.cub.2021.06.045] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
It has long been known that some mouse and vole species have unusual sex chromosomes. A recent genome sequencing study advances understanding of a particularly puzzling vole system.
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Affiliation(s)
- Deborah Charlesworth
- Institute of Evolutionary Biology, School of Biological Sciences, University of Edinburgh, Edinburgh, UK.
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